In an attempt to further the ability to recognize accurately myocardial injury, an improved technique of LDH isoenzyme analysis is employed in serial sample analysis. It is hoped that close correlation of enzyme levels and the patient's clinical picture (including operative method) will show the new technique to be quite sensitive and quite specific. Enzyme levels done by the new assay will be correlated with EKG data and similar comparisons will be made with EKG information and isoenzyme data obtained using the standard techniques available. Blood samples will be obtained pre, intra- and postoperatively (the latter at regular intervals). Samples may be taken on a daily basis until discharge in those patients whose clinical course or electrocardiograms suggest injury.